Generally, a boring machine is a device which drills a deep hole from the ground into the underground for purposes of drilling, soil testing, or development of underground water.
A conventional boring machine is disclosed in Korean Patent Registration No. 10-0624233.
The conventional boring machine includes a body having a driving device such as an engine, a leader supported by the body, and a head sliding along the leader and generating an elevational force or a rotational force by the driving device provided in the body, a rod coupled to the head and being elevated or rotated by the head, and a drilling unit provided at a front end of the rod and drilling the ground while elevating or rotating along with the rod.
The drilling unit includes a bit that drills by striking the ground, and a hammer operated by a fluid pressure to provide a striking force to the bit. Further, the fluid pressure can be transferred to the drilling unit by installing a separate hydraulic line on the rod.
Such a boring machine drills the ground to a predetermined depth through the bit of the drilling unit rotating or striking the ground. When the ground is drilled, the drilling unit and the rod are introduced into the ground. The rod is connected to the drilling unit as much as a depth where the rod is introduced into the ground to extend the length of the rod.
However, since the rod is screw-coupled to the head part in the conventional boring machine, a thread of the drive shaft is worn due to frequent replacement of the rod or the rod or the drive shaft is broken because of excessive fastening of the rod.